Locally positioned em tracker

ABSTRACT

A user console for a surgical robotic system has a seat having an armrest and an electromagnetic (EM) transmitter coupled to the armrest to generate an EM field in an EM tracking space around the armrest. A user input device having a handheld housing is to be positioned within the EM tracking by an operator who is seated in the seat, during a surgical procedure. Other aspects are also described and claimed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is a continuation of co-pendingU.S. patent application Ser. No. 16/440,844, filed on Jun. 13, 2019,which claims the benefit of the earlier filing date of U.S. ProvisionalPatent Application No. 62/685,821 filed on Jun. 15, 2018, and thoseapplications are incorporated herein by reference in their entirety.

FIELD

Embodiments related to robotic systems are disclosed. More particularly,embodiments related to surgical robotic systems and corresponding userinput devices are disclosed.

BACKGROUND INFORMATION

Endoscopic surgery involves looking into a patient's body and performingsurgery inside the body using endoscopes and other surgical tools. Forexample, laparoscopic surgery can use a laparoscope to access and viewan abdominal cavity. Endoscopic surgery can be performed using manualtools and/or a surgical robotic system having robotically-assistedtools.

A surgical robotic system may be remotely operated by a surgeon operatorto control a robotically-assisted tool located at an operating table.The surgeon may use a computer console located in the operating room, orit may be located in a different city, to command a robot to manipulatethe surgical tool mounted on the operating table. Therobotically-controlled surgical tool can be a grasper mounted on arobotic arm. Accordingly, the surgical robotic system may be controlledby the remote surgeon to grasp tissue during a robotic surgery.

Control of the surgical robotic system may require control inputs fromthe surgeon. For example, the surgeon may hold in her hand a user inputdevice, UID, such as a joystick or a computer mouse that she manipulatesto generate the signals based on the system produces control commandsthat control motion of the surgical robotic system components, e.g., anactuator, a robotic arm, and/or a surgical tool of the robotic system.In this manner, the pose of the surgical tool will mimic and follow thepose of the UID.

SUMMARY

In order for the surgical tool to mimic and follow the pose of the UID,the surgical robotic system needs to accurately measure the pose(position and orientation) of the UID. In an electromagnetic tracker, EMtracker, a modulated magnetic field generated in the workspace of thesurgeon operator establishes a reference which is measured by a sensorthat is fixed in the UID. In the case of medical applications, movementsin the sub-millimeter (for translation) and sub-degree (for orientation)range may be required to achieve clinically feasible operation. It isnoted that system noise, which can lead to control errors, may bereduced by filtering the spatial state signal from the UID. Signalfiltering however can introduce latency that has associated undesirableeffects on the stable operation of the robotic end effector or surgicaltool. Accordingly, a noise-free, accurate, and real-time sensingmethodology is needed to detect the status, position, and orientation ofthe UID used for the control of surgical robotic systems.

An embodiment of the invention is a user console for a surgical roboticsystem that has a seat having an armrest and an electromagnetic (EM)transmitter coupled to the armrest to generate an EM field in an EMtracking space around the armrest. This allows the UID to be in thesweet spot of the EM tracker.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention are illustrated by way of example andnot by way of limitation in the figures of the accompanying drawings inwhich like references indicate similar elements. It should be noted thatreferences to “an” or “one” embodiment of the invention in thisdisclosure are not necessarily to the same embodiment, and they mean atleast one. Also, in the interest of conciseness and reducing the totalnumber of figures, a given figure may be used to illustrate the featuresof more than one embodiment of the invention, and not all elements inthe figure may be required for a given embodiment.

FIG. 1 is a pictorial view of an example surgical robotic system in anoperating arena, in accordance with an embodiment.

FIG. 2 is a perspective view of a user console, in accordance with anembodiment.

FIG. 3 is a side view of a user console armrest including a movableelectromagnetic transmitter, in accordance with an embodiment.

DETAILED DESCRIPTION

Embodiments of an electromagnetic tracker (EM tracker) for tracking thepose of a user input device (UID) for controlling a surgical roboticsystem are described. The EM tracker in some cases could also be used tocontrol other medical systems, such as interventional cardiology systemsor medical vision systems, to name only a few possible applications.

In various embodiments, description is made with reference to thefigures. However, certain embodiments may be practiced without one ormore of these specific details, or in combination with other knownmethods and configurations. In the following description, numerousspecific details are set forth, such as specific configurations,dimensions, and processes, in order to provide a thorough understandingof the embodiments. In other instances, well-known processes andmanufacturing techniques have not been described in particular detail inorder to not unnecessarily obscure the description. Reference throughoutthis specification to “one embodiment,” “an embodiment,” or the like,means that a particular feature, structure, configuration, orcharacteristic described is included in at least one embodiment. Thus,the appearance of the phrase “one embodiment,” “an embodiment,” or thelike, in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, configurations, or characteristics maybe combined in any suitable manner in one or more embodiments.

The use of relative terms throughout the description may denote arelative position or direction. For example, “distal” may indicate afirst direction away from a reference point, e.g., away from anoperator. Similarly, “proximal” may indicate a location in a seconddirection opposite to the first direction, e.g., toward the operator.Such terms are provided to establish relative frames of reference,however, and are not intended to limit the use or orientation of a UIDto a specific configuration described in the various embodiments below.

FIG. 1 is a pictorial view of an example surgical robotic system 100 inan operating arena. The robotic system 100 includes a user console 120,a control tower 130, and one or more surgical robotic arms 112 at asurgical robotic platform 111, e.g., a table, a bed, etc. The system 100can incorporate any number of devices, tools, or accessories used toperform surgery on a patient 102. For example, the system 100 mayinclude one or more surgical tools 104 used to perform surgery. Asurgical tool 104 may be an end effector that is attached to a distalend of a surgical arm 112, for executing a surgical procedure.

Each surgical tool 104 may be manipulated manually, robotically, orboth, during the surgery. For example, surgical tool 104 may be a toolused to enter, view, or manipulate an internal anatomy of patient 102.In an embodiment, surgical tool 104 is a grasper that can grasp tissueof patient 102. Surgical tool 104 may be controlled manually, by abedside operator 106; or it may be controlled robotically, via actuatedmovement of the surgical robotic arm 112 to which it is attached.Robotic arms 112 are shown as a table-mounted system, but in otherconfigurations the arms 112 may be mounted in a cart, ceiling orsidewall, or in another suitable structural support.

Generally, a remote operator 107, such as a surgeon or other operator,may use the user console 120 to remotely manipulate the arms 112 and/orsurgical tools 104, e.g., by teleoperation. The user console 120 may belocated in the same operating room as the rest of the system 100, asshown in FIG. 1. In other environments however, the user console 120 maybe located in an adjacent or nearby room, or it may be at a remotelocation, e.g., in a different building, city, or country. The userconsole 120 may comprise a seat 122, foot-operated controls 124, one ormore handheld user input devices, UIDs 126, and at least one operatordisplay 128 configured to display, for example, a view of the surgicalsite inside patient 102. In the example user console 120, remoteoperator 107 is sitting in seat 122 and viewing the operator display 128while manipulating a foot-operated control 124 and a handheld UID 126 inorder to remotely control the arms 112 and surgical tools 104 (that aremounted on the distal ends of the arms 112). Foot-operated control(s)124 can be foot pedals, such as seven pedals, that generate motioncontrol signals when actuated. User console 120 may include one or moreadditional input devices, such as a keyboard or a joystick, to receivemanual inputs to control operations of user console 120 or surgicalrobotic system 100. The operator 107 may hold the UID 126 betweenseveral fingers of her hand, while being able to freely move the UID 126as a whole within a workspace. The workspace may be a range of armsreach of the operator. The UID 126 may be unrestricted by mechanicallinkages that constrain a size of the workspace (also referred to hereas an ungrounded UID).

In some variations, bedside operator 106 may also operate system 100 inan “over the bed” mode, in which bedside operator 106 is now at a sideof patient 102 and is simultaneously manipulating a robotically-driventool (end effector attached to arm 112), e.g., with a handheld UID 126held in one hand, and a manual laparoscopic tool. For example, thebedside operator's left hand may be manipulating the handheld UID 126 tocontrol a robotic component, while the bedside operator's right hand maybe manipulating a manual laparoscopic tool. Thus, in these variations,bedside operator 106 may perform both robotic-assisted minimallyinvasive surgery and manual laparoscopic surgery on patient 102.

During an example procedure (surgery), patient 102 is prepped and drapedin a sterile fashion, and administered anesthesia. Initial access to thepatient anatomy can be achieved using known techniques, such as byforming an incision in the skin. A trocar and/or other surgical tool canbe inserted into the incision through the optical entry in the patient.The trocar can then be positioned at the surgical site. Initial accessto the surgical site may be performed manually while the arms of therobotic system 100 are in a stowed configuration or withdrawnconfiguration (to facilitate access to the surgical site) or in anoperator-defined parking pose. Once initial access is completed, initialpositioning or preparation of the robotic system including its arms 112may be performed. Next, the surgery proceeds with the remote operator107 at the user console 120 utilizing the foot-operated controls 124 andthe UIDs 126 to manipulate the various end effectors and perhaps animaging system, to perform the surgery. Manual assistance may also beprovided at the procedure bed or table, by sterile-gowned bedsidepersonnel, e.g., bedside operator 106 who may perform tasks such asretracting tissues, performing manual repositioning, and tool exchangeupon one or more of the robotic arms 112. Non-sterile personnel may alsobe present to assist remote operator 107 at the user console 120. Whenthe procedure or surgery is completed, the system 100 and/or userconsole 120 may be configured or set in a state to facilitatepost-operative procedures such as cleaning or sterilization andhealthcare record entry or printout via user console 120.

In one embodiment, remote operator 107 holds and moves UID 126 toprovide an input command to move a robot arm actuator 114 in roboticsystem 100. UID 126 may be communicatively coupled to the rest ofrobotic system 100, e.g., via a console computer system 110. UID 126 cangenerate spatial state signals corresponding to movement of UID 126,e.g., position and orientation of the handheld housing of the UID, andthe spatial state signals may be input signals to control a motion ofthe robot arm actuator 114. Robotic system 100 may produce controlsignals as a function of the spatial state signals, to controlproportional motion of actuator 114. In one embodiment, a consoleprocessor of console computer system 110 receives the spatial statesignals and generates the corresponding control signals. Based on thesecontrol signals, which control how the actuator 114 is energized to movea segment or link of arm 112, the movement of a corresponding surgicaltool including an end effector that is attached to the arm may mimic themovement of UID 126. Similarly, interaction between remote operator 107and UID 126 can generate, for example, a grip control signal that causesa jaw of a grasper of the surgical tool to close and grip the tissue ofpatient 102.

The sensed motion of UID 126 may alternatively be provided to controlother aspects of surgical robotic system 100. For example, gesturesdetected by a finger clutch may generate a clutch signal to pause themotion of actuator 114 and the corresponding surgical tool 104. Forexample, when an operator touches the finger clutch of UID 126 with afinger, the finger clutch may generate a clutch signal, and the clutchsignal may be an input signal to pause the motion of actuator 114.Similarly, one or more capacitive sensing pads may be located on UID126, and the operator may touch the capacitive sensing pads to control acamera view of an endoscope, a cursor on a display of user console 120,etc., while performing a diagnostic, surgical, laparoscopic, orminimally invasive surgical procedure, or another robotic procedure.

Surgical robotic system 100 may include several UIDs 126 whererespective control signals are generated for each UID that control theactuators and the surgical tool (end effector) of a respective arm 112.For example, remote operator 107 may move a first UID 126 to control themotion of actuator 114 that is in a left robotic arm, where the actuatorresponds by moving linkages, gears, etc., in that arm 112. Similarly,movement of a second UID 126 by remote operator 107 controls the motionof another actuator 114, which in turn moves other linkages, gears,etc., of the robotic system 100. Robotic system 100 may include a rightarm 112 that is secured to the bed or table to the right side of thepatient, and a left arm 112 that is at the left side of the patient. Anactuator 114 may include one or more motors that are controlled so thatthey drive the rotation of a joint of arm 112, to for example change,relative to the patient, an orientation of an endoscope or a grasper ofthe surgical tool that is attached to that arm. Motion of severalactuators 114 in the same arm 112 can be controlled by the spatial statesignals generated from a particular UID 126. UIDs 126 can also controlmotion of respective surgical tool graspers. For example, each UID 126can generate a respective grip signal to control motion of an actuator,e.g., a linear actuator that opens or closes jaws of the grasper at adistal end of the surgical tool to grip tissue within patient 102.

In some aspects, the communication between platform 111 and user console120 may be through a control tower 130, which may translate operatorcommands that are received from user console 120 (and more particularlyfrom console computer system 110) into robotic control commands that aretransmitted to arms 112 on robotic platform 111. The control tower 130may also transmit status and feedback from platform 111 back to userconsole 120. The communication connections between the robotic platform111, user console 120, and control tower 130 may be via wired and/orwireless links, using any suitable ones of a variety of datacommunication protocols. Any wired connections may be optionally builtinto the floor and/or walls or ceiling of the operating room. Roboticsystem 100 may provide video output to one or more displays, includingdisplays within the operating room as well as remote displays that areaccessible via the Internet or other networks. The video output or feedmay also be encrypted to ensure privacy and all or portions of the videooutput may be saved to a server or electronic healthcare record system.

It will be appreciated that the operating room scene in FIG. 1 isillustrative and may not accurately represent certain medical practices.

Referring to FIG. 2, a perspective view of an example of the userconsole 120 is shown in accordance with an embodiment. As describedabove, the UID 126 can include an electromagnetic sensor (EM sensor, notshown) that interacts with an electromagnetic field (EM field) of theworkspace of the operator 107 to generate a spatial state signal. Moreparticularly, the EM field can be generated by one or more EMtransmitters 18 located on or around the user console 120, and ispresent within an EM tracking space or volume for example as see in FIG.2.

The user console 120 can include a base 12 to support the seat 122 and astand 22 to support the display 128 of the surgical robotic system, asshown. In one embodiment, the base 12 or the stand 22 also supports thefoot-operated controls 124. The remote operator 120 may sit on thegenerally horizontal seat portion of the seat 122, while viewing thedisplay 128 during a surgical procedure and holding the UID 126 in herhand. The user console 120 can include a tracking subsystem to monitormovement of the UID 126. For example, the tracking subsystem may be anEM tracking subsystem or EM tracker, having an EM source, a UID-mountedEM sensor, and processing electronics (e.g., part of the consolecomputer system 110) that prepares a spatial state signal that mayoriginate from the UID-mounted EM sensor (e.g., digitizes and filters asensor output signal of the EM sensor.) The spatial state signalmonitors movement of the UID 126, which is associated with one of thearms 112 (e.g., a separate UID is associated with each surgical roboticarm 112.) The EM source can generate an EM field in an EM trackingspace, while the remote operator 107 is holding the UID 126 within theEM tracking space as shown. The EM tracking space may be the workspacewithin which the remote operator 107 moves the UID 126 while held in herhand, to generate the spatial state signal. The EM tracking space isthus said to be in front of the backrest portion of the seat 122, andmore specifically in front of the operator 107 when seated in the seat122. A digital control system (e.g., a microelectronic processor that isexecuting instructions stored in memory as part of the surgical roboticsystem, for instance in the control tower 130) generates controlcommands to drive various actuators 114 in the robotic arm 112. Thesecontrol commands are responsive to the spatial state signal produced bythe EM tracking subsystem (that originates from the UID 126 that isassociated with the particular arm 112.) The control commands aregenerated in accordance with a digital control algorithm and aredesigned to drive the actuators 114 to cause a corresponding movement ofthe surgical tool 104 that is attached to the associated arm 112 (duringthe surgical procedure.)

The user console 120 may include a source of an electromagnetic fieldused by the EM tracking subsystem to track the pose of the UID 126. Thesource can be one or more EM transmitters 18 used as a field generatorto generate a position varying magnetic field that establishes acoordinate space or frame of reference. The EM transmitter(s) 18 cangenerate the electromagnetic field within the EM tracking space.

In an embodiment, the seat 122 of the user console includes an armrest19. One or more EM transmitters 18 can be integrated with the armrest 18as shown. For example, an EM transmitter may be mounted on the armrest19 to generate the EM tracking space around the armrest. The operator107 will typically hold the UID 126 in her hand and therefore near thedistal end of the armrest 19 while seated, where the distal end is thefree end of the armrest 19 that is furthest from the seated operator 107and the proximal end is the opposite end which is attached to the seat122 or the base and is closest to the seated operator 107. As a result,the EM field is localized so that the UID 126 will mostly remain in asub-volume (of the EM tracking space) that is associated with or yieldsthe lowest tracking error from the EM tracking subsystem. Moreparticularly, the EM tracking space exhibits good quality within aspherical field portion existing around the distal end of the armrest,and thus, the UID that is held in that spherical field (near the distalend of the armrest) may have improved tracking quality due to a lowproximity between the EM sensor that is inside the UID 126 and the EMtransmitters 18 that generate the EM field.

The EM tracking sensor that is a housing of the UID 126 can be amagnetic tracking probe capable of measuring 6 degrees of freedom withinthe EM tracking space. The EM sensor can be a sensor containing coils inwhich current is induced via the electromagnetic field produced by theEM transmitter 18 in the EM tracking space. The tracking sensor can havea known response to the electromagnetic field, and the response may bemeasured as an electrical signal across the coils of the EM sensor. Byinterpreting such coil signal behavior, a position and orientation ofthe EM sensor, and thus the pose of the UID, can be determined. Themeasured response of the EM sensor may be output to the console computersystem as the EM spatial state signal representing movement of the UIDwithin the EM tracking space.

The seat 122 can include several EM transmitters 18. For example, theseat may have a second armrest, and a second EM transmitter may bemounted on the second armrest as shown in FIG. 2. The second EMtransmitter can generate a field in a second EM tracking space aroundthe second armrest. The transmitter 18 in the left armrest 18 produces aleft EM tracking space in which a UID 126 is positioned in the left handof the operator 107 (while seated), while the transmitter in the rightarmrest produces a right EM tracking space in which another UID 126 ispositioned in the right hand of the seated operator 107. Accordingly,several EM tracking sub volumes with low tracking errors can belocalized to the areas where each of several UIDs are held,respectively, during the surgical operation.

In another embodiment, the EM tracking space (field) shown in FIG. 2 isproduced by an EM transmitter 18 that is located in a seat back (orbackrest) portion of the seat 122, as also shown in FIG. 2. That figurealso shows another embodiment where the EM tracking space shown isproduced by an EM transmitter 18 that is mounted in the horizontal seatportion (on which the buttocks of the operator 107 are resting duringthe surgery procedure.) Yet another embodiment depicted in FIG. 2 is onein which the EM tracking space is produced by an EM transmitter 18 thatis mounted to the stand 12 at a position below the operator display 128,at a height above the ground (on which the base 12 or the stand 22rests) that is closer to the bottom of the display 128 than to theground. Still another embodiment is shown in FIG. 2, where a pair oftransmitters 18 are mounted at the bottom of the operator display 128(below the main view screen of the display 128), one to the left of acenter line and another to the right, that produce the EM trackingspace.

Referring to FIG. 3, a side view of another example user console armrest19 is shown, including a movable EM transmitter 18 in accordance with anembodiment. Here, the EM transmitter 18 is mounted on a movablestructure that moves relative to the armrest 19. For example, the userconsole 120 can include a boom 25 that is pivotally connected to thearmrest 19 and on which the EM transmitter 18 is mounted as shown. Moreparticularly, the boom 25 can be connected to the distal end of thearmrest 19 such that a distal end of the boom 25 can follow an arcaround the distal end of the armrest. The EM transmitter 18 can bemounted on the boom 25, e.g., near the distal end of the boom. The EMtransmitter can generate the EM tracking space around the distal end ofthe boom.

In an embodiment, the operator 107 can adjust the boom to a positionthat moves the EM tracking space to a location that coincides with theUID. For example, if the operator prefers to rest his forearms on thearmrest during the surgical operation, the boom can be rotated downwardto the location indicated by dotted lines such that the EM trackingspace coincides with the UID in front of the distal end of the armrest,as in FIG. 3. Accordingly, the operator can adjust the EM tracking spaceenvelope to cover a region where the UID is held. This allows the UID tobe in the sweet spot of the EM tracker. In an alternative embodiment,the movable EM transmitter may be located on another component of theuser console. For example, the boom may be connected to the base 12 orthe display 128 of the user console 120. The boom can pivot about aconnection point, e.g., move in an arc relative to the display.Similarly, the boom may have a telescoping mechanism to allow the EMtransmitter to move axially (in a longitudinal direction) relative tothe base component or the connection point. Accordingly, the EMtransmitter can be moved to a preferred location to generate a localizedEM field for UID tracking.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

1. (canceled)
 2. A user console for a surgical robotic system,comprising: a seat having armrests and a backrest; a display in front ofthe seat; and a plurality of electromagnetic (EM) transmittersconfigured to generate an EM tracking space envelope between thearmrests, the backrest, and the display.
 3. The user console of claim 2,wherein the plurality of EM transmitters includes one or more armrest EMtransmitters mounted on respective free ends of the armrests to generaterespective EM fields localized around the free ends in the EM trackingspace envelope.
 4. The user console of claim 3 further comprising a boommounted on one of the armrests, wherein the boom is movable relative tothe armrests, and wherein one of the one or more armrest EM transmittersare mounted on the boom.
 5. The user console of claim 2, wherein theplurality of EM transmitters includes a backrest EM transmitter mountedon the backrest to generate a respective EM field in the EM trackingspace envelope in front of the backrest.
 6. The user console of claim 2further comprising a stand on which the display is supported; andwherein the plurality of EM transmitters includes a stand EM transmittermounted on the stand to generate a respective EM field in the EMtracking space envelope in front of the seat.
 7. The user console ofclaim 6, wherein the stand EM transmitter is positioned at a heightabove the ground on which the stand is to rest that is closer to thebottom of the display than to the ground.
 8. The user console of claim2, wherein the plurality of EM transmitters includes a display EMtransmitter mounted on the display to generate a respective EM field inthe EM tracking space envelope in front of the seat.
 9. The user consoleof claim 8, wherein the display EM transmitter is mounted closer to thebottom of the display than to the top of the display.
 10. The userconsole of claim 2 further comprising a user input device (UID) havingan EM sensor within a housing to generate a spatial state signal in sixdegrees of freedom that is responsive to the EM tracking space envelopewhile the UID is being held in a hand of an operator and is locatedwithin the EM tracking space envelope.
 11. A surgical robotic system,comprising: a robotic arm including an actuator; a user consoleincluding a seat having armrests and a backrest, a display in front ofthe seat, and a plurality of electromagnetic (EM) transmittersconfigured to generate an EM tracking space envelope between thearmrests, the backrest, and the display; a user input device (UID)having a housing and an EM sensor within a housing to generate a spatialstate signal in six degrees of freedom that is responsive to the EMtracking space envelope; and a control system including one or moreprocessors configured to generate control commands to drive the actuatorbased on the spatial state signal.
 12. The surgical robotic system ofclaim 11, wherein the plurality of EM transmitters includes one or morearmrest EM transmitters mounted on respective free ends of the armreststo generate respective EM fields localized around the free ends in theEM tracking space envelope.
 13. The surgical robotic system of claim 12further comprising a boom mounted on one of the armrests, wherein theboom is movable relative to the armrests, and wherein one of the one ormore armrest EM transmitters are mounted on the boom.
 14. The surgicalrobotic system of claim 11, wherein the plurality of EM transmittersincludes a backrest EM transmitter mounted on the backrest to generate arespective EM field in the EM tracking space envelope in front of thebackrest.
 15. The surgical robotic system of claim 11 further comprisinga stand on which the display is supported; and wherein the plurality ofEM transmitters includes a stand EM transmitter mounted on the stand togenerate a respective EM field in the EM tracking space envelope infront of the seat.
 16. The surgical robotic system of claim 11, whereinthe plurality of EM transmitters includes a display EM transmittermounted on the display to generate a respective EM field in the EMtracking space envelope in front of the seat.
 17. A non-transitorycomputer-readable medium storing instructions which, when executed byone or more processors of a surgical robotic system, cause the surgicalrobotic system to perform a method, comprising: generating, by aplurality of electromagnetic (EM) transmitters of a user console of thesurgical robotic system, an EM tracking space envelope between armrestsof a seat, a backrest of the seat, and a display in front of the seat;generating, by a user input device (UID) having an EM sensor within ahousing, a spatial state signal in six degrees of freedom that isresponsive to the EM tracking space envelope; and generating controlcommands to drive an actuator of the surgical robotic system based onthe spatial state signal.
 18. The non-transitory computer-readablemedium of claim 17, wherein the plurality of EM transmitters includesone or more armrest EM transmitters mounted on respective free ends ofthe armrests to generate respective EM fields localized around the freeends in the EM tracking space envelope.
 19. The non-transitorycomputer-readable medium of claim 17, wherein the plurality of EMtransmitters includes a backrest EM transmitter mounted on the backrestto generate a respective EM field in the EM tracking space envelope infront of the backrest.
 20. The non-transitory computer-readable mediumof claim 17 further comprising a stand on which the display issupported; and wherein the plurality of EM transmitters includes a standEM transmitter mounted on the stand to generate a respective EM field inthe EM tracking space envelope in front of the seat.
 21. Thenon-transitory computer-readable medium of claim 17, wherein theplurality of EM transmitters includes a display EM transmitter mountedon the display to generate a respective EM field in the EM trackingspace envelope in front of the seat.